Digital signal processors and/or micro-controllers are being increasingly used in many commercial products. In this connection, it is common practice to assign a plurality of different tasks to the signal processors or micro-controllers, which requires a not inconsiderable computing capacity. However, this computing capacity varies, depending on the respective tasks to be processed. As a rule, a high computing capacity automatically implies a correspondingly higher energy uptake as well as a higher build-up of heat. Consequently, a technology which saves on energy is extremely important in the case of battery-operated or accumulator-operated products, not only to secure as long as possible an operating time in battery mode on the one hand, but also to avoid an unnecessary build-up of heat on the other.
A known method of reducing the energy uptake of a digital signal processor or micro-processor is to reduce the clock frequency of the processor so that the available computing capacity is adapted to a worst-case requirement in terms of computing power for the respective algorithm or program being run. In principle, the maximum computing capacity necessary for each program run or for each algorithm run is summed and the clock frequency is adapted to this computing capacity. As a rule, however, algorithms and programs require far less than the worst-case computing capacity on average. Consequently, although an energy saving is achieved by this known method, there is still considerable leeway for further energy savings.
Another method of reducing energy uptake is based on stopping the clock signal of the signal processor or micro-controller when all tasks have been processed. This being the case, the clock signal continues to be stopped until one of the programs to be run or one of the algorithms to be run requires processor capacity again. Since the signal processor or micro-controller is either fully active or totally inactive with this method, current peaks occur when the signal processor or micro-controller is activated or deactivated. Particularly in situations where the signal processor or micro-controller is designed as an integrated circuit on a semiconductor chip or forms part of such a circuit, this can cause problems because the extreme modulation of the power uptake can lead to cross-coupling with other components, for example with analogue-to-digital converters or digital-to-analogue converters.